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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Remote sensing of atmospheric aerosol distributions using supervised texture classification

Wiltshire, Ben January 2012 (has links)
This thesis presents a new technique to identify a 2D mask showing the extent of particulate aerosol distributions in satellite imagery. This technique uses a supervised texture classication approach, and utilises data from two distinct satellite sources. The vertical feature mask (VFM) product from the CALIPSO lidar, provides an accurate description of the aerosol content of the atmosphere but has a limited footprint and coverage. The CALIPSO VFM is used to provide training data in order to for classiers to be applied to other imagery, namely data from the spinning enhanced visible and infrared imager (SEVIRI) on the MSG satellite. The output from the classication is a 2D mask representing the locations of the particulate aerosol of interest within the SEVIRI image. This approach has been demonstrated on test cases over land and ocean, and shows a good agreement with other techniques for the detection of particulate aerosol. However, the supervised texture approach provides outputs at a higher resolution than the existing methods and the same approach is applicable over land and ocean and therefore shows the advantages compared to the current techniques. Furthermore, the coverage of the approach can be further extended using signature extension and chain classication. Signature extension was applied to one of the test cases to monitor the same geographical region with temporal extension away from the initial supervised classication. The experiments showed that it was possible to extend the coverage for ±90 minutes from the original classication and indicates the possibility of greater extension over larger temporal windows.
2

The suitability of optical particle counters for covariance estimates of the dry deposition velocity of particulate aerosols

Hubbe, John McBain 12 June 1984 (has links)
Experimental work at the 1982 Dry Deposition Intercomparison Experiment (DDIEx) involved the use of optical particle counters for covariance estimates of dry deposition velocities of accumulation mode aerosols. Meteorological and particle flux observations are presented. Deposition velocity estimates exhibit scatter about zero. A formulation of the standard error of the deposition velocity estimator is derived and examined. Using this formulation, the observed deposition velocities are shown to be marginally significant. Using a case study, the correlation coefficient is examined and presented as an important statistic to the work. Humidity effects on the measurements are briefly examined. Recommendations are made for improvements in the instrumentation. / Graduation date: 1985

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